Pictures: DSC button and flap lifted
Modern VHF radio with GPS feature (Icom 323G)

MMSI ‘s and your Marine Radio & Instruments: What does it all mean?
by Leigh Brennan -Smith, Royal Melbourne Sail Training Academy

Dollar for dollar, marine radios are one of the best safety devices for boat owners to have installed and know how to use them. You can get the latest weather forecast, contact friends on the water or make a distress call if you’re in serious trouble. Many of you will be secure in the knowledge that you’ve got a marine radio onboard your boat with the latest DSC capability. Or have you?
Whilst there’s no restriction on who can buy and install the average VHF marine radio, marine radio operator qualifications are required by law in Australian Waters for both VHF (Short Range) and High Frequency (Long Range) marine radios used for coastal or ocean work. 27 mhz users are exempt. I can only guess that the Authorities see more radios installed on boats as a safety bonus, despite knowing that many radio users are unlicensed.

DSC Safety Calling: One of the key technology improvements over the years has been the ability to make a one button distress call through the Digital Selective Calling (DSC) function. On a modern VHF marine radio this is the red flap marked DISTRESS covering a red button. If the radio is fitted correctly and you’re “IN DISTRESS” (remember the definition of distress is: “Grave or imminent danger to the vessel or loss of life”) pushing the DSC button for 5 seconds will send your vessels details and position (if your radio is linked to your GPS) to any other vessel or coast station within radio range and potentially shorten your rescue time. Backed up by a voice Mayday call, you’ll hopefully be assisted quickly. 

The MMSI (Mobile Maritime Safety Indicator) is your boat’s 9 – digit identifier used in the DSC system and to activate your vessel’s AIS (Automatic Identification System) transceiver, if you have this handy new collision avoidance safety system fitted to your boat. Without an MMSI neither DSC or AIS systems will operate on your vessel. The issuing of MMSI’s replaced call signs for VHF marine radios in Australia due to the update to international marine radio communications in the 1990’s, known as GMDSS. High Frequency (HF) or Single Side Band (SSB) long range marine radios still require a marine radio Apparatus Licence (annual fee required to ACMA) and will be allocated a call sign.

To gain an MMSI for your boat you need to apply to AMSA (Australian Maritime Safety Authority) our national maritime safety regulator. Once issued you need to install the allocated MMSI 9 digit number into your marine radio or AIS to activate their respective safety functions. On the MMSI application AMSA asks for a copy of your marine radio operator qualifications, as well as other safety details about your boat and onshore emergency contacts before sending you an MMSI (No marine radio qualifications, see our marine radio courses offered below to get qualified). If you’ve just bought a second – hand boat with a DSC radio or AIS with an MMSI, you will also need to have the MMSI re-allocated to you by AMSA as the new owner, after sending through a copy of your marine radio operator qualifications.
Having taught marine radio courses at RMYS and elsewhere for over 10 years, I have met many boaties around Melbourne who proudly say they’ve got the latest marine radio and navigation gear, but are unaware that without an MMSI installed in their VHF radio they are not able to use the DSC function in a DISTRESS situation. Now with the inproved understanding of the benefits of AIS (in displaying your vessels position to other vessels and seeing other large vessels around you) we’re now teaching as many people to get marine radio qualifications in order to apply for an MMSI to access the AIS safety system, but also unlocking their radio’s DSC capability in the process.

How to check if your VHF radio is DSC equipped and active? Now if I’ve tweaked your curiosity and you’d like to check your own marine radio, it will take approximately one minute when you’re next enjoying your boat. Firstly we’ll check if the DSC functionality is present on your marine radio and secondly, if it’s fitted with a MMSI, allowing the DSC to operate as designed. To check for DSC, look for the red flap on the front face of the marine radio marked DISTRESS (see picture). If it can’t be found it’s unlikely you’ve got a DSC equipped marine radio. Don’t worry too much if you need to upgrade as ICOM have a terrific VHF radio (Model IC -323G shown) with DSC and inbuilt GPS Receiver for under $400. If YES to the DSC flap, look for the MMSI number starting with 503 in the start – up text scrolling when you first turn on the radio. Alternatively you could check the back – function buttons on the radio for the MMSI. If in doubt look up your radio’s manual (RTM as we say!). No manual; find a copy of your marine radio manual online and print it out to keep it on the boat – alongside your Marine Radio Operators Handbook, a copy of which must be onboard. 

Going back to the inbuilt GPS receiver in a modern marine radio, this is a relatively new function that’s worth looking for if you’re thinking of upgrading your boats radio. Many people with DSC equipped marine radios have not got around to connecting their boat’s GPS to their radio, reducing the safety effectiveness of having DSC by NOT sending out a position in a distress situation. Having the GPS receiver built in to your marine radio means your Lat/Long position is ALWAYS present in any DSC Distress Alert signal sent out, plus you also have the benefit of second back -up GPS if your primary navigation GPS fails.
Knowing how to use the marine radio may one day save your life or put your family at ease knowing you’re safe. The time to learn how to use your marine radio is when you’re having a quiet day in dock doing some maintenance – not when you’ve got water streaming in late one night about to cover the marine batteries! It’s also a great safety tip to have as many people onboard a boat qualified to use the marine radio. Remember skipper’s are not exempt from falling overboard (some might ACT like a god!) or that your allocated radio operator may be sick in his bunk too ill to function.

Hopefully we’ve now dispelled some myths about MMSI’s and DSC. If you’re in doubt please contact Leigh Brennan-Smith on 0412 196301 or email if I can answer any questions for you. For more information, please think about doing a marine radio course – it ‘s a pretty cheap skills investment to improve your safety. 

Background: Royal Melbourne Sail Training Academy teaches Marine Radio evening courses at RMYS throughout the year. You’ll be taught both theory and the practical aspects about using your marine radio, as well as finding out about DISTRESS calling, EPIRB rescue beacons and AIS. Our radio courses use ICOM marine radios (both VHF and HF) in the classroom to ensure you’re trained on the latest equipment by experienced offshore marine radio operators. We offer the internationally approved SHORT RANGE qualification (VHF only) as well as the LONG RANGE qualification (VHF + HF) for coastal and ocean use, with courses starting from $265 including the official handbook and exam fee. Our next Marine Radio course starts Thursday 19 th July, 2018 at 7 pm.

Leigh Brennan -Smith, Royal Melbourne Sail Training Academy